require 'rest_client'
require 'singleton'
require 'flydata/credentials'
require 'flydata/helpers'

module Flydata
  FLYDATA_API_HOST = ENV['FLYDATA_API_HOST'] || 'https://flydata.co'

  class ApiClient
    include Singleton
    include Helpers
    attr_reader :response
    attr_accessor :credentials
    attr_reader :flydata_api_host

    def initialize
      @credentials = Flydata::Credentials.new
      read_flydata_api_host
    end

    # row level api
    def post(path, headers = nil, params=nil)
      uri = generate_auth_url(path)
      resource = RestClient::Resource.new(uri, resource_opts(headers))
      @response = resource.post(params, :accept => :json)
      handle_response response
    end
    def put(path, params=nil)
      uri = generate_auth_url(path)
      resource = RestClient::Resource.new(uri, resource_opts)
      @response = resource.put(params, :accept => :json)
      handle_response response
    end
    def get(path)
      uri = generate_auth_url(path)
      resource = RestClient::Resource.new(uri, resource_opts)
      @response = resource.get(:accept => :json)
      handle_response response
    end

    # high level api
    def method_missing(cls_name, *args, &block)
      method_name = args.shift.to_s
      require File.join("flydata/api", cls_name.to_s)
      api_cls = "Flydata::Api::#{cls_name.to_s.camelize}".constantize
      api_cls.new(self)
    end
    def respond_to_missing?(method_name, include_private=false); true end

    private
    def read_flydata_api_host
      if FileTest.exist?(flydata_api_host_file)
        File.open(flydata_api_host_file, 'r') do |f|
          @flydata_api_host = f.gets.chomp
          @flydata_api_host = FLYDATA_API_HOST unless @flydata_api_host and not @flydata_api_host.empty?
        end
      else
        @flydata_api_host = FLYDATA_API_HOST
      end
      # delete the '/'
      @flydata_api_host = @flydata_api_host[0..-2] if @flydata_api_host =~ /\/$/
    end

    def handle_response(response)
      json_response = JSON.parse(response)
      if json_response.class == Hash and json_response["success"] == false
        err_msg = json_response['errors'] ? json_response['errors'].to_s : "Unkown error."
        raise err_msg
      elsif json_response.class == Hash and json_response["auth_token"]
        @credentials.write_credentials(json_response["auth_token"])
      end
      json_response
    end
    def resource_opts(headers=nil)
      # merge headers and default parameter
      parameters = {}
      parameters.merge(headers) if headers
    end
    def generate_auth_url(path)
      token = @credentials.token
      token = '' unless token
      c = (path && path.include?('?')) ? '&' : '?'
      "#{@flydata_api_host}#{path}#{c}auth_token=#{token}"
    end
  end
end